This proposal concerns Ca dynamics during mouse egg fertilization. The project focuses on spatial and temporal changes in [Ca2+]i in mouse (not starfish) oocytes during fertilization. This project brings together two strong PIs with expertise in both the modeling of calcium signals and in oocyte cell biology. Its direct relevance to the calcium dynamics core project implies a strong synergism between this collaborative project and the calcium core project. The project aims to employ a finite element modeling method within the Virtual Cell framework to compute calcium dynamics in mouse oocytes based on the measured distribution of the ER and of the cell overall. Five major hypotheses are proposed, all of which are based on experimental protocols that are within the expertise of the PIs. Although it is implied rather than explicitly stated, the outcomes of these experiments will drive the modeling half of the proposal. Particular strengths of this project include the proven techniques of ER imaging and localized Ca changgs,aind the novel aspects of both of these components in this project.